The present invention relates to a method for preparing suspensions of materials having low solubility. The present invention also relates to suspensions prepared by such a method.
In many applications, it is often desired to deliver a large amount of a material to a target. For example, in the pharmaceutical art, a sufficiently high dose of an active ingredient delivered to a target tissue is typically required to provide an effective treatment of a disorder. Such a sufficient dose may be achieved through a sufficiently high concentration of the active ingredient in the formulation for a short time or, alternatively, through sustained delivery of a lower concentration for an extended time.
Many active pharmaceutical ingredients (“APIs”) have low solubility in commonly used media such as aqueous compositions. Therefore, such APIs are often formulated into suspensions containing particles thereof for sustained delivery and achievement of sufficiently effective doses.
Formulating suspension of low-solubility materials presents many challenges. For example, in one aspect, the efficacy of a pharmaceutical suspension is related to the particle size of the API. Typically, better pharmaceutical suspensions are achieved with smaller particles and more uniform size because of higher and more consistent release rate. However, pulverization of solid APIs to obtain small particles may lead to excessive local temperature increase and agglomeration.
Poor physical stability is another challenge. Larger particles of a population having wide particle size distribution can settle out of the suspension and are not easily resuspended, leading to undesirable variable drug dosages when administered to a patient.
Therefore, there is a continued need to provide improved suspensions containing APIs having low solubility. It is also desirable to provide methods for preparing improved suspensions that, avoid at least some of the problems of prior-art methods.